Connecting to a Spin App¶

In order to be able to access your application from outside of Spin (for example from a web browser, over the Internet) you must tell Spin how to route incoming requests. This can be done by configuring an Ingress. It is similar to the configuration used by a web server, which translates URLs to file system paths.

HTTP-based services: Ingresses¶

If you want users to access an endpoint that speaks the HTTP protocol (ie. a web server, or an API), go to the Resources menu, select Workloads and then click the Load Balancer tab. Click Add Ingress, give the ingress a name, select the namespace serviced by the ingress and check Specify a hostname to use.

For Request Host, enter the following (substitute your information as needed):

<name>.<namespace>.<environment>.svc.spin.nersc.org

Where:

• name can be anything (except contain a period)

• namespace is the selected namespace

• environment is the current one ("production" or "development")

• Note that the domain ends in ".org" not ".gov"

Next, leave path blank, select the HTTP-based workload you want to access and enter a port.

Click "Save" and wait for the state to go from "Initializing" to "Ready". Wait another 1-5 mins for DNS to propagate and then try accessing your app at

http://<name>.<namespace>.<environment>.svc.spin.nersc.org:<port>

HTTPS access and Custom DNS names¶

DOE security requirements dictate that web services must be encrypted using a web certificate. Generally, obtaining a certificate will be done in conjunction with obtaining a custom DNS name for your app. Processes for obtaining certificates and registering DNS names vary from institution to institution, so check with your local IT support or project collaborators for guidance.

Your custom DNS name should simply be a CNAME record to the long, generated name above ending in svc.spin.nersc.org; for example,

<custom DNS name> CNAME <name>.<namespace>.<environment>.svc.spin.nersc.org

Once you have a web certificate and custom DNS name, edit the ingress and add a rule to specify the DNS name to use and select the same port and target as the ingress. You should now be able to access your application via:

http://<custom DNS name>

To install the web certificate, click "Resources", select "Secrets" and click the "Certificates" tab. Click "Add Certificate" and enter the private key and the certificate. Next go to "Workloads", select "Load Balancing", find and edit your ingress and select the certificate in the "SSL/TLS" panel. You should now be able to access your application via:

https://<custom DNS name>

Non-HTTP services: Load Balancers¶

Services such as MySQL, PostgreSQL and other non-HTTP applications can also be opened to other networks at NERSC. Note that access to these applications are restricted to NERSC networks only, although we are working on a method to expose these services to other facilities.

For this example, let's assume that you have set up a mysql workload called db and want to make connect to it from the Cori or Spin login nodes.

Edit your db workload, and add the following to Port Mapping, and hit Save:

• Port Name: mysql
• Publish the container port: 3306
• Protocol: TCP
• As a Layer-4 Load Balancer
• On listening port: 3306

Notice that your workload now has loadbalancer Service called db-loadbalancer and its state is active. The service will have an automatically generated name in the format <workload>-loadbalancer. Spin will automatically generate the DNS hostname for your service, in the following format:

<workload>-loadbalancer.<namespace>.<environment>.svc.spin.nersc.org

Click on ⋮ > Edit of the db-loadbalancer, click on Show advanced options and open Labels and Annotations. Notice that the hostname for your service is automatically set with the following annotation. This is the hostname to use for accessing your application.

external-dns.alpha.kubernetes.io/hostname=<name>.<namespace>.<environment>.svc.spin.nersc.org

Optionally, click on the Service Discovery tab and notice there are two Services: db that exposes a port within your namespace, and db-loadbalancer which is the same service that you saw under the Load Balancing tab.

External Traffic Policy¶

A feature called External Traffic Policy controls how traffic from sources outside of Spin is routed to your application. There are two choices:

• The Local policy is is faster then Cluster, as your loadbalancer endpoint will reside on the same node as your service. It will also preserve the client source IP for applications that need it.
• The Cluster policy provides better network redundancy, but at the expense of one network hop which reduces performance. It also obscures the client soucre IP.

For most services, we recommend that you set this to Local. To do this, on your loadbalancer service, click on ⋮ > Edit. Scroll down to External Traffic Policy and select Local.

To connect to your external hostname, use the above hostname and the application port. For example for a hypothetical mysql workload:

mysqlsh -h db-loadbalancer.<namespace>.<environment>.svc.spin.nersc.org -u root